基于多PK-PD模型联合研究细梗香草抗肿瘤体内药效物质基础及其作用机制

Total saponins of L. capillipes Hemsl extract (LCE) showed significant antitumor activities in previous studies. However, the poor bioavailability of both capilliposide B(LC-B) and capilliposide C(LC-C), the major bioactive chemical components in LCE, could not explain the pharmacological effects of LCE orally administered in vivo. The metabolites of LC-C transformed by rat intestinal microflora showed significant antitumor activities, which indicated their metabolites may be related to its efficacy. Increasing attention is being paid on the PK-PD modeling used to study the pharmacodynamic basis of herbal medicines and its mechanism. However, the pharmacokinetic study of major components of herbal medicines has difficulties in fully understanding their absorption, distribution, metabolism and excretion. The empirical models of tumor growth kinetics could not describe the physiological processes and illustrate their mechanism of action. In the present study, an LC-MS/MS-MRM method based on metabolic profiling of LCE will be used to uniquely characterize and quantitate individual parent and metabolites. Furthermore, we will establish PK-PD models using Simeoni TGI model and empirical models of biomarkers, respectively. Then, the pharmacodynamic basis and mechanism of LCE will be clarified via the analyses of “drug-to-tumor” and “drug-to-biomarker” relationship, characteristic model parameters and the correlation. In conclusion, this study will provide scientific evidences for further use of L. capillipes Hemsl and also provide a novel strategy for developing antitumor herbal medicines.

细梗香草总皂苷抗肿瘤效果显著，其主要成分细梗香草皂苷B和C生物利用度低于1%，体内药效物质基础尚未明确。前期工作发现，细梗香草皂苷C的肠道菌群转化产物抑制多种肿瘤细胞增殖，提示代谢产物与其药效相关。基于PK-PD结合模型研究中药药效物质及作用机制日益受到重视。然而基于中药主要成分的PK研究，难以全面揭示药物的体内过程。基于肿瘤生长动力学的经验模型，忽视肿瘤生长过程，无法阐明作用机制。本项目拟建立能特异性表征和定量体内暴露组分的基于LC-MS/MS-MRM的细梗香草皂苷代谢轮廓谱分析方法，进而应用整合药代动力学方法分别构建基于Simeoni TGI模型和肿瘤生物标志物经验模型的PK-PD结合模型。通过“药物-肿瘤”、“药物-生物标志物”动态变化过程、特征模型参数及相关性分析，全面揭示细梗香草体内药效物质基础及作用机制。本项目不仅为细梗香草开发提供科学依据，更为拓展抗肿瘤中药研发思路提供支持。

细梗香草总皂苷抗肿瘤效果显著，其主要成分细梗香草皂苷B和C生物利用度低于1%，其体内药效物质基础尚未明确。前期工作发现，细梗香草皂苷C的肠道菌群转化产物抑制多种肿瘤细胞增殖，提示代谢产物与其药效相关。本课题采用PK-PD结合模型研究细梗香草总皂苷体内抗肿瘤药效物质及其作用机制。首先，采用肠道菌群孵育将细梗香草总皂苷转化为其代谢产物，评价肠道菌群转化产物的体外抗肿瘤活性，发现转化产物对PC-3、SK-OV-3和SW620肿瘤细胞较为敏感。其次，小鼠经口给药10天后，采用LC-MS鉴定血浆、尿液和粪便中的代谢产物，共检测到15个代谢产物。综合代谢产物鉴定结果，建立基于LC-MS/MS-MRM特征性代谢轮廓谱分析方法并进行整合药代动力学研究。药效动力学模型采用荷瘤小鼠模型给药，结果显示细梗香草总皂苷肠道菌群转化产物能够抑制显著荷瘤裸鼠肿瘤的生长。于此同时，对肿瘤组织（SK-OV-3荷瘤小鼠模型）中的生物标志物检测发现，其可上调LC-3B蛋白的表达。在整合药代动力学和药效动力学研究基础上，构建基于Simeoni TGI模型的PK-PD模型，发现整合药代动力学血药浓度高于肿瘤凋亡临界药物浓度的暴露成分中，体内代谢产物C52H86O23的权重系数最高。其后，通过碱水解方法由细梗香草总皂苷肠道菌群转化产物制备、分离该代谢产物，采用质谱、核磁方法确证其结构。制备代谢产物的体外活性评价和机制研究结果显示，对SW620细胞的IC50为7.6 μM，其可以降低SW620细胞中PI3K、p-Akt及p-mTOR表达。因此，推测其通过干预PI3K/Akt/mTor细胞信号转导通路，从而干扰细胞的生存调节。

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